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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | WARNING | AUTHOR | AVAILABILITY | SEE ALSO | COLOPHON |
BADBLOCKS(8) System Manager's Manual BADBLOCKS(8)
badblocks - search a device for bad blocks
badblocks [ -svwnfBX ] [ -b block_size ] [ -c blocks_at_once ] [ -d
read_delay_factor ] [ -e max_bad_blocks ] [ -i input_file ] [ -o
output_file ] [ -p num_passes ] [ -t test_pattern ] device [
last_block ] [ first_block ]
badblocks is used to search for bad blocks on a device (usually a
disk partition). device is the special file corresponding to the
device (e.g /dev/hdc1). last_block is the last block to be checked;
if it is not specified, the last block on the device is used as a
default. first_block is an optional parameter specifying the
starting block number for the test, which allows the testing to start
in the middle of the disk. If it is not specified the first block on
the disk is used as a default.
Important note: If the output of badblocks is going to be fed to the
e2fsck or mke2fs programs, it is important that the block size is
properly specified, since the block numbers which are generated are
very dependent on the block size in use by the filesystem. For this
reason, it is strongly recommended that users not run badblocks
directly, but rather use the -c option of the e2fsck and mke2fs
programs.
-b block_size
Specify the size of blocks in bytes. The default is 1024.
-c number of blocks
is the number of blocks which are tested at a time. The
default is 64.
-d read delay factor
This parameter, if passed and non-zero, will cause bad blocks
to sleep between reads if there were no errors encountered in
the read operation; the delay will be calculated as a
percentage of the time it took for the read operation to be
performed. In other words, a value of 100 will cause each read
to be delayed by the amount the previous read took, and a
value of 200 by twice the amount.
-e max bad block count
Specify a maximum number of bad blocks before aborting the
test. The default is 0, meaning the test will continue until
the end of the test range is reached.
-f Normally, badblocks will refuse to do a read/write or a non-
destructive test on a device which is mounted, since either
can cause the system to potentially crash and/or damage the
filesystem even if it is mounted read-only. This can be
overridden using the -f flag, but should almost never be used
--- if you think you're smarter than the badblocks program,
you almost certainly aren't. The only time when this option
might be safe to use is if the /etc/mtab file is incorrect,
and the device really isn't mounted.
-i input_file
Read a list of already existing known bad blocks. Badblocks
will skip testing these blocks since they are known to be bad.
If input_file is specified as "-", the list will be read from
the standard input. Blocks listed in this list will be
omitted from the list of new bad blocks produced on the
standard output or in the output file. The -b option of
dumpe2fs(8) can be used to retrieve the list of blocks
currently marked bad on an existing filesystem, in a format
suitable for use with this option.
-n Use non-destructive read-write mode. By default only a non-
destructive read-only test is done. This option must not be
combined with the -w option, as they are mutually exclusive.
-o output_file
Write the list of bad blocks to the specified file. Without
this option, badblocks displays the list on its standard
output. The format of this file is suitable for use by the -l
option in e2fsck(8) or mke2fs(8).
-p num_passes
Repeat scanning the disk until there are no new blocks
discovered in num_passes consecutive scans of the disk.
Default is 0, meaning badblocks will exit after the first
pass.
-s Show the progress of the scan by writing out rough percentage
completion of the current badblocks pass over the disk. Note
that badblocks may do multiple test passes over the disk, in
particular if the -p or -w option is requested by the user.
-t test_pattern
Specify a test pattern to be read (and written) to disk
blocks. The test_pattern may either be a numeric value
between 0 and ULONG_MAX-1 inclusive, or the word "random",
which specifies that the block should be filled with a random
bit pattern. For read/write (-w) and non-destructive (-n)
modes, one or more test patterns may be specified by
specifying the -t option for each test pattern desired. For
read-only mode only a single pattern may be specified and it
may not be "random". Read-only testing with a pattern assumes
that the specified pattern has previously been written to the
disk - if not, large numbers of blocks will fail verification.
If multiple patterns are specified then all blocks will be
tested with one pattern before proceeding to the next pattern.
-v Verbose mode. Will write the number of read errors, write
errors and data- corruptions to stderr.
-w Use write-mode test. With this option, badblocks scans for bad
blocks by writing some patterns (0xaa, 0x55, 0xff, 0x00) on
every block of the device, reading every block and comparing
the contents. This option may not be combined with the -n
option, as they are mutually exclusive.
-B Use buffered I/O and do not use Direct I/O, even if it is
available.
-X Internal flag only to be used by e2fsck(8) and mke2fs(8). It
bypasses the exclusive mode in-use device safety check.
Never use the -w option on a device containing an existing file
system. This option erases data! If you want to do write-mode
testing on an existing file system, use the -n option instead. It is
slower, but it will preserve your data.
The -e option will cause badblocks to output a possibly incomplete
list of bad blocks. Therefore it is recommended to use it only when
one wants to know if there are any bad blocks at all on the device,
and not when the list of bad blocks is wanted.
badblocks was written by Remy Card <Remy.Card@linux.org>. Current
maintainer is Theodore Ts'o <tytso@alum.mit.edu>. Non-destructive
read/write test implemented by David Beattie <dbeattie@softhome.net>.
badblocks is part of the e2fsprogs package and is available from
http://e2fsprogs.sourceforge.net.
e2fsck(8), mke2fs(8)
This page is part of the e2fsprogs (utilities for ext2/3/4
filesystems) project. Information about the project can be found at
⟨http://e2fsprogs.sourceforge.net/⟩. It is not known how to report
bugs for this man page; if you know, please send a mail to
man-pages@man7.org. This page was obtained from the project's
upstream Git repository
⟨git://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git⟩ on 2017-07-05.
If you discover any rendering problems in this HTML version of the
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send a mail to man-pages@man7.org
E2fsprogs version 1.43.5-WIP February 2017 BADBLOCKS(8)
Pages that refer to this page: e2fsck(8), mke2fs(8), mkfs(8)